1 /*- 2 * Copyright (c) 2006,2008 Joseph Koshy 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <gelf.h> 28 29 #include "_libelf.h" 30 31 ELFTC_VCSID("$Id: libelf_checksum.c 3174 2015-03-27 17:13:41Z emaste $"); 32 33 static unsigned long 34 _libelf_sum(unsigned long c, const unsigned char *s, size_t size) 35 { 36 if (s == NULL || size == 0) 37 return (c); 38 39 while (size--) 40 c += *s++; 41 42 return (c); 43 } 44 45 long 46 _libelf_checksum(Elf *e, int elfclass) 47 { 48 size_t shn; 49 Elf_Scn *scn; 50 Elf_Data *d; 51 unsigned long checksum; 52 GElf_Ehdr eh; 53 GElf_Shdr shdr; 54 55 if (e == NULL) { 56 LIBELF_SET_ERROR(ARGUMENT, 0); 57 return (0L); 58 } 59 60 if (e->e_class != elfclass) { 61 LIBELF_SET_ERROR(CLASS, 0); 62 return (0L); 63 } 64 65 if (gelf_getehdr(e, &eh) == NULL) 66 return (0); 67 68 /* 69 * Iterate over all sections in the ELF file, computing the 70 * checksum along the way. 71 * 72 * The first section is always SHN_UNDEF and can be skipped. 73 * Non-allocatable sections are skipped, as are sections that 74 * could be affected by utilities such as strip(1). 75 */ 76 77 checksum = 0; 78 for (shn = 1; shn < e->e_u.e_elf.e_nscn; shn++) { 79 if ((scn = elf_getscn(e, shn)) == NULL) 80 return (0); 81 if (gelf_getshdr(scn, &shdr) == NULL) 82 return (0); 83 if ((shdr.sh_flags & SHF_ALLOC) == 0 || 84 shdr.sh_type == SHT_DYNAMIC || 85 shdr.sh_type == SHT_DYNSYM) 86 continue; 87 88 d = NULL; 89 while ((d = elf_rawdata(scn, d)) != NULL) 90 checksum = _libelf_sum(checksum, 91 (unsigned char *) d->d_buf, (size_t) d->d_size); 92 } 93 94 /* 95 * Return a 16-bit checksum compatible with Solaris. 96 */ 97 return (long) (((checksum >> 16) & 0xFFFFUL) + (checksum & 0xFFFFUL)); 98 } 99